The present invention relates generally to optical communication systems, and, more particularly to a method and structure for coupling optical fibers with printed wiring board embedded waveguides.
There are many well-recognized benefits of using optical fiber to replace copper wiring for printed circuit boards (PCBs) in computer and networking equipment. Such potential benefits include increased bandwidth and data rate, overcoming bottlenecks in the processing architecture, immunity to electromagnetic interference and reductions in radiated noise from the system, reduced latency by elimination of optical/electrical (O/E) conversions, more dense packaging at lower cost per pin, and enablement of new processor interconnect technologies such as meshed rings. These and other factors directly contribute to the performance of the computer system (e.g., increased processing power in MIPS (million instructions per second) or FLOPS (floating-point operations per second), increased node count in parallel architectures, etc.).
With the dramatic increase in processor speed over the last several years and the anticipation that this trend will continue, the copper interconnect technology will be unable to scale to the bandwidth requirements of the processing units. Fiber optic components, on the other hand, do not suffer from the bandwidth/distance constraints of copper and are thus becoming a preferred medium for very high bandwidth transmission between processing units. But, in order to fully realize these benefits, the optical fiber interconnect components should also continue to provide benefits of the existing electrical connection technologies.
Currently, there are no known available methods for directly coupling light from an incoming fiber to embedded waveguides formed within a printed wiring board (PWB) substrate. Instead, conventional connector assemblies focus on fiber-to-fiber coupling.
For example, U.S. Pat. No. 6,402,393 to Grimes, et al. discloses an interconnection system for optical circuit boards having a number of optical devices that are connected to and disconnected from a backplane. The optical circuit boards use jack receptacles affixed to the edge of the circuit board for making connection to the backplane, which contains an array of optical plugs. The corresponding optical plugs and jacks are not individually interlocked when coupled, thus facilitating removal of the optical circuit board from the backplane.
U.S. Pat. No. 6,412,986 to Ngo, et al. discloses an adapter for ganging multiple optical connectors together. The adapter includes a frame for mounting to a printed circuit board and at least one adapter housing movably mounted in a receiving area of the frame. The adapter housing is sized and shaped to receive two or more optical connectors therein and individually connect the optical connectors to the adapter housing. The optical connectors are received in opposite directions into the adapter housing and connect to each other inside the adapter housing.
U.S. Patent Application Publication US 2003/0095758 by Morse, et al. is directed toward an optical connector adapter for interfacing single or multichannel devices to fiber. The adaptor is provided with a substrate for transporting optical signals, and having opposing ends, a top reference surface and a single side surface. A substrate carrier receives the substrate and a carrier bracket that is received over the top reference surface of the substrate using carrier alignment fiducials. However, the Morse disclosure still does not provide a direct interface between, for example, a fiber optic connector and optical waveguides formed within a printed wiring board.
U.S. Pat. No. 6,302,590 to Moore discloses an optical connector featuring a housing portion with a first bay for engaging a plug having a waveguide. The first bay is partially open at a proximal end and has a wall at a distal end thereof. A chamber adjoins the first bay at the wall, and has an optical pathway therein. In addition, at least two external passive alignment pins are integrally formed with the first bay for engaging recesses in a first plug. The external passive alignment pins passively align the waveguide to the optical pathway, and an opening in the wall allows for transmission of an optical signal along the optical pathway between the first plug and the chamber.
U.S. Pat. No. 5,155,784 to Knott is directed toward an optical connection means between an optical guide carried by a circuit board and an optical guide carried by or associated with a backplane. The connection means includes a two-part plug and socket mechanical connector in combination with a two-part plug and socket optical fiber connector. One part of the mechanical connector is moveable to a limited extent with respect to the carrying circuit board or backplane, while the other part is fixedly secured thereto. One part of the optical fiber connector is housed and fixedly secured to the fixed part of the mechanical connector, while the other part of the optical fiber connector is slidably mounted in the moveable part of the mechanical connector.
Accordingly, it would be desirable to be able to conveniently and reliably couple/decouple light from optical fiber connector to embedded PWB waveguides in a manner compatible with existing connector technology.